United States 

Environmental Protection 

Agency 

1200 Pennsylvania Avenue, N.W. 

Washington, D.C. 20460 

September 

2011 

Office of Solid Waste and Emergency Response 

Support Document for the 

Revised National Priorities List 

Final Rule – Armstrong World Industries
Armstrong World Industries NPL Listing Support Document September 2011 

Support Document for the 

Revised National Priorities List 

Final Rule 

Armstrong World Industries 

September 2011 

Site Assessment and Remedy Decisions Branch 

Office of Superfund Remediation and Technology Innovation 

Office of Solid Waste and Emergency Response 

U.S. Environmental Protection Agency 

Washington, DC 20460
Armstrong World Industries NPL Listing Support Document September 2011 

Table of Contents

Executive Summary.................................................................................................................................... ii

Introduction ............................................................................................................................................... iii

Background of the NPL .......................................................................................................................... iii

Development of the NPL ........................................................................................................................ iii

Hazard Ranking System.......................................................................................................................... iv

Other Mechanisms for Listing ................................................................................................................. v

Organization of this Document................................................................................................................ v

Glossary .................................................................................................................................................. vi

1. List of Commenters and Correspondence ....................................................................................... 1

2. Site Description .................................................................................................................................. 1

3. Summary of Comments..................................................................................................................... 1

3.1 Support for listing......................................................................................................................... 2

3.2 Site Name ..................................................................................................................................... 2

3.3 Liability ........................................................................................................................................ 3

3.4 Hazardous Substances Associated With Sources......................................................................... 3

3.5 Source Hazardous Waste Quantity ............................................................................................... 4

3.6 Probable Points of Entry from Sources ........................................................................................ 9

3.7 Attribution .................................................................................................................................. 10

4. Conclusion ........................................................................................................................................ 13

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Armstrong World Industries NPL Listing Support Document September 2011 

Executive Summary 

Section 105(a)(8)(B) of CERCLA, as amended by SARA, requires that the EPA prepare a list of national 

priorities among the known releases or threatened releases of hazardous substances, pollutants, or contaminants 

throughout the United States. An original National Priorities List (NPL) was promulgated on September 8, 1983 

(48 FR 40658). CERCLA requires that EPA update the list at least annually. 

This document provides responses to public comments received on the Armstrong World Industries site, proposed 

on October 21, 2010 (75 FR 64976). This site is being added to the NPL based on an evaluation under EPA’s 

Hazard Ranking System (HRS) in a final rule published in the Federal Register in September 2011. 

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Armstrong World Industries NPL Listing Support Document September 2011 

Introduction 

This document explains the rationale for adding the Armstrong World Industries site in Macon, Georgia, to the 

National Priorities List (NPL) of uncontrolled hazardous waste sites and provides responses to public comments 

received on this site listing proposal. The EPA proposed this site to the NPL on October 21, 2010 (75 FR 64976). 

This site is being added to the NPL based on an evaluation under the Hazard Ranking System (HRS) in a final 

rule published in the Federal Register in September 2011. 

Background of the NPL 

In 1980, Congress enacted the Comprehensive Environmental Response, Compensation, and Liability Act 

(CERCLA), 42 U.S.C. Sections 9601 et seq. in response to the dangers of uncontrolled hazardous waste sites. 

CERCLA was amended on October 17, 1986, by the Superfund Amendments and Reauthorization Act (SARA), 

Public Law No. 99-499, stat., 1613 et seq. To implement CERCLA, EPA promulgated the revised National Oil 

and Hazardous Substances Pollution Contingency Plan (NCP), 40 CFR Part 300, on July 16, 1982 (47 FR 31180), 

pursuant to CERCLA Section 105 and Executive Order 12316 (46 FR 42237, August 20, 1981). The NCP, 

further revised by EPA on September 16, 1985 (50 FR 37624) and November 20, 1985 (50 FR 47912), sets forth 

guidelines and procedures needed to respond under CERCLA to releases and threatened releases of hazardous 

substances, pollutants, or contaminants. On March 8, 1990 (55 FR 8666), EPA further revised the NCP in 

response to SARA. 

Section 105(a)(8)(A) of CERCLA, as amended by SARA, requires that the NCP include 

criteria for determining priorities among releases or threatened releases throughout the United 

States for the purpose of taking remedial action and, to the extent practicable, take into account 

the potential urgency of such action, for the purpose of taking removal action. 

Removal action involves cleanup or other actions that are taken in response to emergency conditions or on a 

short-term or temporary basis (CERCLA Section 101). Remedial action is generally long-term in nature and 

involves response actions that are consistent with a permanent remedy for a release (CERCLA Section 101). 

Criteria for placing sites on the NPL, which makes them eligible for remedial actions financed by the Trust Fund 

established under CERCLA, were included in the HRS. EPA promulgated the HRS as Appendix A of the NCP 

(47 FR 31219, July 16, 1982). On December 14, 1990 (56 FR 51532), EPA promulgated revisions to the HRS in 

response to SARA, and established the effective date for the HRS revisions as March 15, 1991. 

Section 105(a)(8)(B) of CERCLA, as amended, requires that the statutory criteria provided by the HRS be used to 

prepare a list of national priorities among the known releases or threatened releases of hazardous substances, 

pollutants, or contaminants throughout the United States. The list, which is Appendix B of the NCP, is the NPL. 

An original NPL of 406 sites was promulgated on September 8, 1983 (48 FR 40658). At that time, an HRS score 

of 28.5 was established as the cutoff for listing because it yielded an initial NPL of at least 400 sites, as suggested 

by CERCLA. The NPL has been expanded several times since then, most recently on March 10, 2011 (76 FR 

13089). The Agency also has published a number of proposed rulemakings to add sites to the NPL. The most 

recent proposal was on March 10, 2011 (76 FR 13113). 

Development of the NPL 

The primary purpose of the NPL is stated in the legislative history of CERCLA (Report of the Committee on 

Environment and Public Works, Senate Report No. 96-848, 96th Cong., 2d Sess. 60 [1980]). 

iii 
Armstrong World Industries NPL Listing Support Document September 2011 

The priority list serves primarily informational purposes, identifying for the States and the public 

those facilities and sites or other releases which appear to warrant remedial actions. Inclusion of 

a facility or site on the list does not in itself reflect a judgment of the activities of its owner or 

operator, it does not require those persons to undertake any action, nor does it assign liability to 

any person. Subsequent government actions will be necessary in order to do so, and these actions 

will be attended by all appropriate procedural safeguards. 

The NPL, therefore, is primarily an informational and management tool. The identification of a site for the NPL 

is intended primarily to guide EPA in determining which sites warrant further investigation to assess the nature 

and extent of the human health and environmental risks associated with the site and to determine what CERCLAfinanced remedial action(s), if any, may be appropriate. The NPL also serves to notify the public of sites EPA 

believes warrant further investigation. Finally, listing a site may, to the extent potentially responsible parties are 

identifiable at the time of listing, serve as notice to such parties that the Agency may initiate CERCLA-financed 

remedial action. 

CERCLA Section 105(a)(8)(B) directs EPA to list priority sites among the known releases or threatened release 

of hazardous substances, pollutants, or contaminants, and Section 105(a)(8)(A) directs EPA to consider certain 

enumerated and other appropriate factors in doing so. Thus, as a matter of policy, EPA has the discretion not to 

use CERCLA to respond to certain types of releases. Where other authorities exist, placing sites on the NPL for 

possible remedial action under CERCLA may not be appropriate. Therefore, EPA has chosen not to place certain 

types of sites on the NPL even though CERCLA does not exclude such action. If, however, the Agency later 

determines that sites not listed as a matter of policy are not being properly responded to, the Agency may consider 

placing them on the NPL. 

Hazard Ranking System 

The HRS is the principle mechanism EPA uses to place uncontrolled waste sites on the NPL. It is a numerically 

based screening system that uses information from initial, limited investigations -- the preliminary assessment and 

site inspection -- to assess the relative potential of sites to pose a threat to human health or the environment. HRS 

scores, however, do not determine the sequence in which EPA funds remedial response actions, because the 

information collected to develop HRS scores is not sufficient in itself to determine either the extent of 

contamination or the appropriate response for a particular site. Moreover, the sites with the highest scores do not 

necessarily come to the Agency's attention first, so that addressing sites strictly on the basis of ranking would in 

some cases require stopping work at sites where it was already underway. Thus, EPA relies on further, more 

detailed studies in the remedial investigation/feasibility study that typically follows listing. 

The HRS uses a structured value analysis approach to scoring sites. This approach assigns numerical values to 

factors that relate to or indicate risk, based on conditions at the site. The factors are grouped into three categories. 

Each category has a maximum value. The categories are: 

• likelihood that a site has released or has the potential to release hazardous substances into the 

environment; 

• characteristics of the waste (toxicity and waste quantity); and 

• people or sensitive environments (targets) affected by the release. 

Under the HRS, four pathways can be scored for one or more threats as identified below: 

• Ground Water Migration (Sgw) 

- drinking water 

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Armstrong World Industries NPL Listing Support Document September 2011 

• Surface Water Migration (Ssw) 

The following threats are evaluated for two separate migration components, overland/flood migration and 

ground water to surface water. 

- drinking water 

- human food chain 

- sensitive environments 

• Soil Exposure (Ss) 

- resident population 

- nearby population 

- sensitive environments 

• Air Migration (Sa) 

- population 

- sensitive environments 

After scores are calculated for one or more pathways according to prescribed guidelines, they are combined using 

the following root-mean-square equation to determine the overall site score (S), which ranges from 0 to 100: 

4

S + S + S + S = S

2

a

2

s

2

sw

2

gw

If all pathway scores are low, the HRS score is low. However, the HRS score can be relatively high even if only 

one pathway score is high. This is an important requirement for HRS scoring because some extremely dangerous 

sites pose threats through only one pathway. For example, buried leaking drums of hazardous substances can 

contaminate drinking water wells, but -- if the drums are buried deep enough and the substances not very volatile 

-- not surface water or air. 

Other Mechanisms for Listing 

There are two mechanisms other than the HRS by which sites can be placed on the NPL. The first of these 

mechanisms, authorized by the NCP at 40 CFR 300.425(c)(2), allows each State and Territory to designate one 

site as its highest priority regardless of score. The last mechanism, authorized by the NCP at 40 CFR 

300.425(c)(3), allows listing a site if it meets the following three requirements: 

• Agency for Toxic Substances and Disease Registry (ATSDR) of the U.S. Public Health Service has 

issued a health advisory that recommends dissociation of individuals from the release; 

• EPA determines the site poses a significant threat to public health; and 

• EPA anticipates it will be more cost-effective to use its remedial authority than to use its emergency 

removal authority to respond to the site. 

Organization of this Document 

The following section contains EPA responses to site-specific public comments received on the proposal of the 

Armstrong World Industries site on October 21, 2010 (75 FR 64976). The site discussion begins with a list of 

commenters, followed by a site description, a summary of comments, and Agency responses to each comment. A 

concluding statement indicates the effect of the comments on the HRS score for the site. 

v 
Armstrong World Industries NPL Listing Support Document September 2011 

vi 

Glossary 

The following acronyms and abbreviations are used throughout the text: 

Agency U.S. Environmental Protection Agency 

AIP Allied Industrial Park 

AWI Armstrong World Industries

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act of 1980, 42 

U.S.C. Sections 9601 et seq., also known as Superfund 

CFR Code of Federal Regulations 

EPA U.S. Environmental Protection Agency 

ESI Expanded Site Investigation 

FR Federal Register 

FMNOL Former Macon Naval Ordinance Landfill 

FMNOP Former Macon Naval Ordinance Plant 

HRS Hazard Ranking System, Appendix A of the NCP 

HRS score Overall site score calculated using the Hazard Ranking System; ranges from 0 to 100 

MDL Method detection limit 

NCP National Oil and Hazardous Substances Pollution Contingency Plan, 40 C.F.R. Part 300 

NPL National Priorities List, Appendix B of the NCP 

PAH Polycyclic aromatic hydrocarbon 

PCB Polychlorinated biphenyl 

PPE Probable point of entry 

PRP Potentially responsible party 

RCRA Resource Conservation and Recovery Act 

RI/FS Remedial investigation and feasibility study 

SARA Superfund Amendments and Reauthorization Act 

SI Site Inspection 

START Superfund Technical Assistance and Response Team 

SVOC Semi-volatile organic compound 

TDL Target Distance Limit 

VOC Volatile organic compound 

WWTP Wastewater Treatment Plant
Armstrong World Industries NPL Listing Support Document September 2011 

1. List of Commenters and Correspondence 

EPA-HQ-SFUND-0640-0006 Comment Submitted by Steven Pfeiffenberger, Vice President, 

Environment, Health, and Safety, Armstrong World Industries, Inc. 

(AWI) 

 

EPA-HQ-SFUND-0640-0005 Comment Submitted by Bonnie Allyn, Barnett, Drinker Biddle & Reath 

LLP on behalf of Steven Pfeiffenberger, Vice Presidnet, Environment, 

Health & Safety, Armstrong World Industries, Inc. (AWI) 

EPA-HQ-SFUND-0640-0004 Letter to A. Stanley Meiburg, Acting Regional Administrator, Region 4, 

USEPA, from F. Allen Barnes, Director, Georgia Department of Natural 

Resources 

2. Site Description 

The Armstrong World Industries site (AWI site) consists of three sources and associated releases of hazardous 

substances to the surface water migration pathway. All three sources are documented to contain hazardous 

substances from deposited waste as a result of operations at the AWI facility. Specifically, polychlorinated 

biphenyls (PCBs) have been associated with operations at the AWI facility, such as the processing of newspaper 

print (inks). Source 1, a wastewater treatment plant (WWTP) landfill located on the AWI facility, was 

documented as containing hazardous substances including PCBs. Overland flow from Source 1 migrates into a 

drainage ditch which conveys surface water toward wetlands and Rocky Creek, a human food chain fishery. 

Source 2, the combined AWI remote landfill and Former Macon Naval Ordnance Landfill (FMNOL), contains 

hazardous substances resulting from activities at the AWI facility and the Former Macon Naval Ordnance Plant 

(FMNOP). Source 3, contaminated soil surrounding the AWI remote landfill, is documented as containing 

hazardous substances including semi-volatile organic compounds (SVOCs), metals and PCBs. Overland flow 

from these sources migrates into wetlands and Rocky Creek. Portions of Source 3 were documented as located 

directly within wetlands, establishing an observed release by direct observation. 

An observed release by chemical analysis has been established as release samples within Rocky Creek, located 

downgradient of site sources, contained hazardous substances (including PCBs that have been associated with 

AWI facility operations) significantly greater than background levels and the increase is due at least in part to 

releases from the AWI site. 

Targets associated with surface water contamination were identified in the HRS evaluation of this site. Rocky 

Creek is fished for human consumption within the zone of contamination. The Ocmulgee River is a source for 

outdoor recreation, comprising approximately 9 miles of the 15-mile target distance limit (TDL). Further, 

approximately 1.94 miles of wetland frontage has been identified as subject to Level II concentrations. 

3. Summary of Comments 

Comments were submitted by Drinker, Biddle & Reath LLP on behalf of Armstrong World Industries, Inc. (AWI) 

challenging the listing of Armstrong World Industries site (AWI site) on the National Priorities List (NPL). 

AWI commented on its concern regarding the site name, asserting that the HRS evaluation of the AWI site 

includes sources not associated with AWI. As such, AWI suggested that the EPA rename the site after the “point 

of exposure,” rather than Armstrong World Industries. 

 

AWI stated that particular products discussed in the HRS documentation record as containing polychlorinated 

biphenyls (PCBs) were not produced or recycled at AWI’s Macon, Georgia facility, and are not a source of PCBs 

1 
Armstrong World Industries NPL Listing Support Document September 2011 

at the site. Further, AWI challenged the evaluation of source hazardous waste quantity for the sources at the site. 

AWI stated that contamination cannot be considered contiguous between sampling points at Sources 1 and 2 in 

the HRS evaluation, since contamination was not considered contiguous for Source 3. 

AWI asserted that certain probable points of entry (PPEs) have been improperly excluded from the delineation of 

the hazardous substance migration pathway. AWI stated that other PPEs not discussed in the HRS documentation 

record are draining areas emanating from other off-site sources of contamination, such as from the Allied 

Industrial Park property1

 (AIP property) located adjacent to the AWI property. As such, AWI asserted that 

“premature conclusions” regarding attribution at the site have been made, and that the ambiguity of origin of 

contamination at the site warrants further data collection and evaluation before liability is assigned. 

3.1 Support for listing 

Comment: The State of Georgia submitted a letter (dated July 6, 2010) to the the EPA Region 4 Administrator 

stating that the State agrees that the Site poses a significant threat to the public health and the environment and 

supports the EPA's efforts to propose the Site for inclusion on the NPL. 

Response: The Armstrong World Industries site is being added to the NPL. Listing makes a site eligible for 

remedial actions under CERCLA, and the EPA will examine the Site to determine what response, if any, is 

appropriate. Actual funding may not necessarily be undertaken in the precise order of HRS scores, however, and 

upon more detailed investigation may not be necessary at all in some cases. The EPA will determine the need for 

Superfund monies for remedial activities on a site-by-site basis, taking into account the NPL ranking, State 

priorities, further site investigation, other response alternatives, and other factors as appropriate. The EPA will not 

stop work at some sites to begin work at other higher-scoring sites added to the NPL more recently. 

3.2 Site Name 

Comment: Armstrong World Industries (AWI) expressed concern regarding the site name. AWI asserted that two 

of the three identified sources - Source 2 (the Former Macon Naval Ordinance Landfill or FMNOL) and Source 3 

(contaminated soil surrounding Source 2) include sources other than AWI, namely the owners and operators of 

the FMNOL, as well as other potential sources to Rocky Creek from the surrounding area. AWI asserted that “it 

would be more appropriate to name the site after the point of exposure (the Rocky Creek Superfund Site) rather 

than after only one of a number of possible sources,” noting precedent for this approach. AWI requested that 

rename the site or at least include in the site name a reference to the FMNOL and related facilities. 

Response: The site name of Armstrong World Industries has been retained. Names are preferred that accurately 

reflect the location or nature of the problems at a site and that are readily and easily associated with a site by the 

general public. As such, the name chosen reflects the long operational history of Armstrong World Industries at 

the Macon facility. 

Regarding AWI’s comment that Sources 2 and 3 “include sources other than AWI,” disposal of waste in Source 2 

has been documented as resulting from operations at the AWI facility. Since Source 3 is contaminated soil 

surrounding Source 2, the hazardous substances detected in Source 3 came to be located through migration 

resulting from the erosive processes at Source 2. As processes at the AWI facility are known to have contributed 

hazardous substances to all site sources, the site name is appropriate. 

 

1

 The Allied Industrial Park property (AIP property), located east of the AWI Macon facility, is the location of the Former 

Macon Naval Ordnance Plant (FMNOP). Ordnance was manufactured at the FMNOP. The property is currently owned by 

the Macon-Bibb County Industrial Authority. Various commercial and/or industrial operations currently take place at the AIP 

property. 

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Armstrong World Industries NPL Listing Support Document September 2011 

The name of the site does not in any way restrict the evaluation of the site, its sources, its releases, or extent of 

contamination to only the practices of Armstrong World Industries. As the Federal Register in which the 

Armstrong World Industries site was proposed to the NPL (75 FR 64978, Section F) states, “the precise nature 

and extent of the site are typically not known at the time of listing.” Any and all areas of contamination will be 

explored during investigation activities outside of the listing process. 

The purpose of the NPL is to serve primarily as an informational tool for use in identifying those sites that appear 

to present a significant risk to public health or the environment. The naming of the site does not reflect a judgment 

of the activities of the owner or operator of a site. It does not require those persons to undertake any action, nor 

does it assign liability to any person. 

This comment has no effect on the HRS site score or the decision to place the site on the NPL. 

3.3 Liability 

Comment: While liability concerns were not directly raised by AWI, it stated that “[c]onclusions about likely 

contributions . . . (whether AWI or other potential sources) should await further data collection and evaluation,” 

which could be interpreted as raising concerns about liability. 

Response: Liability is not established by placing a site on the NPL. The NPL serves primarily informational 

purposes, identifying for the States and the public those facilities and sites or other releases which appear to 

warrant remedial actions. Inclusion of a facility or site on the NPL does not in itself reflect a judgment of the 

activities of an owner or operator, it does not require those persons to undertake any action, nor does it assign 

liability to any person. Subsequent government actions will be necessary to do so, and these actions will be 

attended by all appropriate procedural safeguards.

This comment has no effect on the HRS site score or the decision to place the site on the NPL. 

3.4 Hazardous Substances Associated With Sources 

Comment: AWI noted that the HRS documentation record states that three types of ceiling tiles were 

manufactured by AWI (Travertone Sanserra, Santaglio and Embossed Design) and that these tiles were coated 

with a formulation that contained Aroclor-1254, a commercial formulation of PCBs. AWI asserted that these 

products were manufactured for a “very short period of time” and were neither manufactured nor recycled at 

AWIs’ Macon facility. AWI requested that the EPA delete the reference to the ceiling tiles since they are not a 

source of PCBs at the site. 

Response: The HRS documentation record has been revised at promulgation; the discussion regarding the 

handling or processing of the tiles in question has been removed. However, hazardous substances, including 

PCBs, were appropriately associated with Sources 1, 2 and 3. That specific ceiling tile products were or were not 

manufactured or processed at the Macon facility does not impact the association of PCBs with site sources. 

HRS Section 1.1, Definitions, defines source in part as, “Any area where a hazardous substance has been 

deposited, stored, disposed, or placed, plus those soils that have become contaminated from migration of a 

hazardous substance. . .” 

One of the necessary criteria for establishing a site source, as directed by the HRS, involves associating hazardous 

substances with sources. HRS Section 2.2.2, Identify hazardous substances associated with a source, states in 

part: 

Identify hazardous substances associated with a source. For each of the three migration pathways, 

consider those hazardous substances documented in a source (for example, by sampling, labels, 

3 
Armstrong World Industries NPL Listing Support Document September 2011 

manifests, oral or written statements) to be associated with that source when evaluating each 

pathway. 

At this site, sources containing hazardous substances have been identified through sampling. The tables displayed 

in Section 2.2.2 of the HRS documentation record at proposal present (for Sources 1, 2 and 3) that hazardous 

substances, including PCBs, have been detected in the site sources through sampling and analysis. Thus, these 

hazardous substances are associated with site sources (landfills and contaminated soil) and not with a specific 

manufactured product at the facility. 

Whether or not the specific products discussed by the commenter (Travertone Sanserra, Santaglio and Embossed 

Design tiles) were manufactured or recycled at the facility does not discredit the findings that hazardous 

substances (including PCBs) were detected in site sources, nor the establishment of each source. Further, PCBs 

detected in releases downgradient from all site sources are appropriately attributable to the site, as PCBs were 

detected in all site sources that received waste from operations at the AWI facility (see section 3.7 of this support 

document for further discussion on attribution of PCBs to the site). Thus, the discussion of the manufacturing or 

handling of these specific products at the AWI Macon facility does not impact any scoring factor. 

This comment has no effect on the HRS site score or on the decision to place the site on the NPL. 

3.5 Source Hazardous Waste Quantity 

Comment: AWI challenged the evaluation of source hazardous waste quantity for the scored sources. AWI stated 

that waste quantity was not calculated for Source 3 because “it is not known whether contamination in Source No. 

3 is contiguous between sampling points”. AWI further questioned that since it is not known whether 

contamination is contiguous between sampling points for Sources 3 and a waste quantity was not calculated, why 

the same rationale was not used to calculate a source hazardous waste quantity value for Sources 1 and 2. 

Response: The hazardous waste quantity evaluation for each of the site sources was appropriately scored in the 

HRS documentation record at proposal. First, a waste quantity value of “greater than 0” was assigned to Source 3. 

Second, the waste quantities assigned to Sources 1 and 2 were based on the defined boundaries of the waste in 

these landfills using a waste quantity based on the area of the sources. All site sources meet the HRS definition of 

a source. HRS Section 1.1, Definitions, defines “source” as: 

Any area where a hazardous substance has been deposited, stored, disposed, or placed, plus those 

soils that have become contaminated from migration of a hazardous substance. . . . 

HRS Section 2.4.2.1, Source hazardous waste quantity, directs the scorer how to assign a hazardous waste 

quantity value to a source. It states: 

For each of the three migration pathways, assign a source hazardous waste quantity value to each 

source (including the unallocated source) having a containment factor value greater than 0 for the 

pathway being evaluated . . . 

For all pathways, evaluate source hazardous waste quantity using the following four measures in 

the following hierarchy: 

• Hazardous constituent quantity. 

• Hazardous wastestream quantity. 

• Volume. 

• Area. 

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Armstrong World Industries NPL Listing Support Document September 2011 

HRS Section 2.4.2.1.4, Area, directs the evaluator to: 

Evaluate the area measure using the area of the source (or area of the area of the observed 

contamination). Based on this area, designated as A, assign a value to the area measure as 

follows: 

• For the migration pathways, assign the source a value for area using the appropriate Tier 

D equation of Table 2-5. [emphasis added] 

HRS Section 2.4.2.1.5, Calculation of source hazardous waste quantity value, states: 

Select the highest of the values assigned to the source (or area of observed contamination) for the 

hazardous constituent quantity, hazardous wastestream quantity, volume, and area measures. 

Assign this value as the source hazardous waste quantity value. Do not round to the nearest 

integer. 

As presented in Section 2.4.2.1, Source Hazardous Waste Quantity, of the HRS documentation record at proposal, 

the information available was not sufficient to evaluate the hazardous constituent quantity, hazardous wastestream 

quantity, or the volume measures for Sources 1, 2, or 3 (See pages 26, 39 and 50 of the HRS documentation 

record). As such, all site sources were evaluated using the Area measure. 

The following two subsections address how the source hazardous waste quantity was properly evaluated for 

Source 3 and Sources 1 and 2, respectively. 

Source 3 

Source 3, which was evaluated as source type “contaminated soil,” is composed of soil that became contaminated 

due to migration of a hazardous substance. That is, according to the HRS definition of source as quoted above, 

“Any area where a hazardous substance has been deposited, stored, disposed, or placed, plus those soils that 

have become contaminated from migration of a hazardous substance,” [emphasis added] can be considered a 

source. 

As presented on page 50 of the HRS documentation record at proposal a value of “greater than 0” was calculated 

for this source hazardous waste quantity value. This value was assigned because the existence of hazardous 

substances within this source has been established through sampling and analysis (see Table 9 of the HRS 

documentation record at proposal). 

Table 1 below identifies the samples taken from the contaminated soil area. All show significant levels of 

contamination. Thus, the estimate of “greater than 0” is justified. 

5 
Armstrong World Industries NPL Listing Support Document September 2011 

 Table 1: Hazardous Substances Associated with Source 3 

Sample ID

Hazardous 

Substance

Hazardous 

Substance 

Concentration MRL

Source Samples (0 to 6 inches bgs)

PCB-1254 4,000 μg/kg 560 μg/kg 

Cadmium 2.3 mg/kg 0.86 mg/kg 

Lead 57 mg/kg 1.7 mg/kg 

AWI-216-SF 

Manganese 750 mg/kg 2.6 mg/kg 

FML-300-SF Fluoranthene 240 μg/kg 200 μg/kg 

Benzo(a)anthracene 350 μg/kg 230 μg/kg 

Benzo(a)pyrene 560 μg/kg 230 μg/kg 

Benzo(k)fluoranthene 290 μg/kg 230 μg/kg 

Chrysene 560 μg/kg 230 μg/kg 

Fluoranthene 480 μg/kg 230 μg/kg 

Pyrene 470 μg/kg 230 μg/kg 

PCB-1248 2,000J (2,000) 

μg/kg 440 μg/kg 

PCB-1254 1,500 μg/kg 440 μg/kg 

PCB-1260 270 μg/kg 44 μg/kg 

Cadmium 4.5 mg/kg 0.71 mg/kg 

FML-301-SF 

Lead 150 mg/kg 1.4 mg/kg 

PCB-1248 1,200 μg/kg 110 μg/kg 

Cadmium 6.2 mg/kg 1.7 mg/kg 

Lead 90 mg/kg 3.4 mg/kg 

FML-304-SF 

Manganese 2,400 mg/kg 5.1 mg/kg 

PCB-1248 240 μg/kg 63 μg/kg 

Cadmium 1.6 mg/kg 0.95 mg/kg FML-305-SF 

Manganese 3,600 mg/kg 2.9 mg/kg 

PCB-1248 470 μg/kg 110 μg/kg 

Cadmium 7.8 mg/kg 1.7 mg/kg 

Lead 90 mg/kg 3.4 mg/kg 

FML-308-SF 

Manganese 1,800 mg/kg 5.1 mg/kg 

FML-309-SF Cadmium 4.6 mg/kg 2.8 mg/kg 

Lead 57 mg/kg 5.6 mg/kg 

FML-309-SF- Cadmium 6.5 mg/kg 3.2 mg/kg 

DUP Manganese 560 mg/kg 9.7 mg/kg 

Source Samples (12 to 24 inches bgs) 

PCB-1254 1,600 μg/kg 530 μg/kg 

Cadmium 0.87 mg/kg 0.80 mg/kg 

Lead 82 mg/kg 1.6 mg/kg 

AWI-216-SB 

Manganese 1,000 mg/kg 2.4 mg/kg 

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Armstrong World Industries NPL Listing Support Document September 2011 

7 

 Table 1: Hazardous Substances Associated with Source 3 

Sample ID

Hazardous 

Substance

Hazardous 

Substance 

Concentration MRL

Benzo(a)pyrene 310 μg/kg 190 μg/kg 

Chrysene 270 μg/kg 190 μg/kg 

PCB-1248 4,500J (4,500) 

μg/kg 370 μg/kg 

PCB-1260 170 μg/kg 37 μg/kg 

Cadmium 3.9 mg/kg 0.56 mg/kg 

FML-301-SB 

Lead 100 mg/kg 1.1 mg/kg 

Benzo(a)pyrene 16,000 μg/kg 7,400 μg/kg 

PCB-1248 1,500 μg/kg 140 μg/kg 

Cadmium 77 mg/kg 2.6 mg/kg 

Chromium 61 mg/kg 5.1 mg/kg 

FML-304-SB 

Lead 100 mg/kg 5.1 mg/kg 

PCB-1248 110 μg/kg 53 μg/kg 

Cadmium 5.2 mg/kg 0.80 mg/kg 

Lead 36 mg/kg 1.6 mg/kg 

FML-305-SB 

Manganese 410 mg/kg 2.4 mg/kg 

Benzo(a)pyrene 7,100 μg/kg 6,500 μg/kg 

PCB-1248 7,400 μg/kg 1,300 μg/kg 

Cadmium 75 mg/kg 1.8 mg/kg 

Chromium 93 mg/kg 3.7 mg/kg 

FML-308-SB 

Lead 170 mg/kg 3.7 mg/kg 

PCB-1248 9,600 μg/kg 1,700 μg/kg 

Cadmium 110 mg/kg 2.8 mg/kg 

Chromium 100 mg/kg 5.7 mg/kg 

FML-309-SB 

Lead 140 mg/kg 5.7 mg/kg 

However, because all samples taken from Source 3 contained hazardous substances and the area is likely to have 

become contaminated by runoff or other migration from Source 2 (see discussion below regarding Source 2 

contamination), it is reasonable to consider that the area between the sample locations is contaminated and a 

source area could have been measured for Source 3 (see Table 1 above). As such, Figure 1 of this support 

document presents a calculated area measurement of Source 3 which shows that Source 3 is approximately 94,400 

square feet based on the area between locations of four samples taken from Source 3. 

If this calculated area measurement were used in the source hazardous waste quantity evaluation instead of the 

“greater than 0” area calculation used in the HRS documentation record, there would be no impact on the scoring 

of the surface water migration pathway hazardous waste quantity scoring, nor on the site score. That is, if an area 

of 94,000 square feet were assigned to Source 3, then according to Table 2-5 of the HRS, this value would be 

divided by 34,000, yielding an assigned value of 2.776. If this source hazardous waste quantity value were to be 

used in the HRS evaluation, the sum of the source hazardous waste quantity (for all sources) would increase from 

>174.06 to 176.836. According to Table 2-6 of the HRS, the value of 176.836 would still correspond with an 

assigned value of 100 to the pathway hazardous waste quantity evaluation, the same as in the HRS documentation 

record at proposal. 
Armstrong World Industries NPL Listing Support Document 

Figure 1: Source 3 Area Measurement 

 8 
Armstrong World Industries NPL Listing Support Document September 2011 

Sources 1 and 2 

For Sources 1 and 2, the source type is landfill. A landfill is the location of an intended deposition of waste, the 

boundaries of which are known. When evaluating the area of this source, HRS Section 2.4.2.1.4 directs the scorer 

to evaluate the entire area of the source (in this case – landfill), not just the locations of the samples. Multiple 

samples from Sources 1 and 2 were documented to contain hazardous substances (see page 21 through 22 and 33 

through 37 of the HRS documentation record at proposal), thus the area measurement assigned to these sources 

reflects the consideration that the hazardous waste within these sources is continuous. 

AWI’s assertion that contamination should not be inferred between sampling locations at Sources 1 and 2 because 

of the unknown extent of contamination between samples at Source 3 is inconsistent with the HRS, as discussed 

above. Even though a defined area was not assigned to Source 3 in the evaluation of hazardous waste quantity in 

the HRS documentation record at proposal, as discussed above, Source 3 was given a source hazardous waste 

quantity of “greater than 0” and therefore was assigned a value for waste quantity. As such, the way that the 

source hazardous waste quantity was calculated for Source 3 has no effect on the evaluation of hazardous waste 

quantity for Sources 1 and 2. 

Further, given that the Source 3 sample locations came to be contaminated due to runoff from Source 2 toward the 

Source 3 sample locations, the area between the Source 3 sample locations is also in the overland flow path 

emanating from Source 2. Thus, it is reasonable to project contamination between the Source 3 sample locations. 

This comment has no effect on the HRS site score or the decision to place the site on the NPL. 

3.6 Probable Points of Entry from Sources 

Comment: AWI asserted that the delineation of the hazardous substance migration pathway improperly excluded 

probable points of entry (PPEs) from the HRS evaluation. AWI pointed out that Figure 2 of the HRS 

documentation record shows PPE 1, but does not show PPE 2 or PPE 3. 

Response: The PPEs from Sources 1, 2 and 3 were appropriately described and presented in the HRS 

documentation record. AWI has confused PPEs included in the HRS evaluation with what was identified as PPEs 

in the 2009 Site Inspection Report (SI) (as shown on Figure 3 of Reference 7 of the HRS documentation record). 

Not all PPEs identified in the SI report qualify as PPEs for the HRS evaluation. 

PPEs 1 and 2, as scored in this evaluation, are presented on Figure 2 of the HRS documentation record. PPE 1, 

which drains Source 1, is located south and downgradient from Source 1. PPE 2 drains Sources 2 and 3, and is 

evaluated as the interface between Source 2/Source 3 and surface water. Because Sources 2 and 3 are located 

adjacent to and/or within the surface water migration pathway, PPE 2 has been estimated as the interface between 

these sources and surface water. PPE 2 is displayed on Figure 2 of the HRS documentation record as a yellowblack dashed line between surface water and the approximate boundaries of Source 2 and 3 as identified as PPE 2 

in the Legend of Figure 2 of the HRS documentation record at proposal. 

All PPEs were evaluated in accordance with the HRS. HRS Section 4.1.1.1 Definition of hazardous substance 

migration path for overland/flood migration component, states: 

The hazardous substance migration path includes both the overland segment and the in-water 

segment that hazardous substances would take as they migrate away from sources at the site: 

• Begin the overland segment at a source and proceed downgradient to the probable point 

of entry to surface water. 

9 
Armstrong World Industries NPL Listing Support Document September 2011 

For Source 1, Section 4.1.1.1 of the HRS documentation record discusses that overland flow from Source 1 

“enters the drainage ditch that originates in the eastern portion of Source No. 1.” As shown on Figure 2 of the 

HRS documentation record, PPE 1 is located in the drainage ditch just southeast of Source 1. 

From Sources 2 and 3, Section 4.1.1.1 of the HRS documentation record explains that: 

Overland flow from Source No. 2 (the commingled AWI remote landfill and the FMNOL) and 

Source No. 3 (contaminated soil surrounding the commingled landfill) travels south-southeast for 

about 0 to 375 feet into palustrine forested wetlands on the FMNOL property that are contiguous 

with Rocky Creek (Refs. 52; 60). 

Because Sources 2 and 3 are in close proximity with surface water (wetlands) in some locations, and in other 

locations within the wetlands, the interface where overland flow from Sources 2 and 3 meets surface water is 

approximated as the border between the sources and the wetland. This is shown on Figure 2 of the HRS 

documentation record at proposal as PPE 2. 

Within the 2009 Site Inspection Report, the point where drainage ditches 3 and 4 enter Rocky Creek was labeled 

“PPE 2” and “PPE 3” respectively. These drainage ditches were not included in the HRS evaluation as probable 

points of entry associated with sources evaluated as part of the AWI site. These ditches may be conveying 

hazardous substances to Rocky Creek from other off-site sources from the Allied Industrial Park property (AIP 

property); however, the locations where these ditches convey hazardous substances to Rocky Creek are 

downstream of PPEs 1 and 2 and several observed release sample locations and therefore these ditches are not the 

cause of the significant increase in contamination attributed to the AWI site. As explained in section 3.7, 

Attribution, of this support document, the significant increase of hazardous substances to the surface water 

migration pathway has been appropriately attributed in part to AWI site sources. 

This comment has no effect on the HRS site score or the decision to place the site on the NPL. 

3.7 Attribution 

Comment: AWI commented that the Attribution section of the HRS documentation record “draws conclusions 

about sources prematurely,” and asserted that conclusions regarding contribution by sources (whether AWI or 

other potential sources) should await further data collection and evaluation. AWI stated that there are other 

potential contributors of contamination to Rocky Creek from the surrounding area. 

Specifically, AWI stated that it believes that other PPEs are draining areas emanating from the Allied Industrial 

Park property, and that additional sampling is warranted at the Former Naval Ordinance Plant [formerly located at 

the AIP property]. AWI asserted that runoff and/or tributaries from this Former Naval Ordinance Facility should 

be shown on the map, as they may be key points of entry for contaminants. 

Response: At least part of the significant increase of hazardous substances in the observed release samples for the 

surface water migration pathway has been appropriately attributed to AWI. Contamination potentially entering 

Rocky Creek from the FMNOP is entering below the location where observed releases from the AWI site have 

been documented. 

Attribution was established at this site by first documenting that hazardous substances in the releases are 

associated with the site by showing that the contaminants are associated with site sources; second, by showing 

that hazardous substances were directly placed in surface water; and third, by documenting that there is no 

evidence suggesting that the significant increase in contaminant concentrations came from off-site sources. At this 

site, an observed release by chemical analysis has been established and the significant increase of hazardous 

substances has been attributed to AWI. Additionally, there is evidence of direct deposition of hazardous 

substances into the surface water from sources associated with AWI. 

10 
Armstrong World Industries NPL Listing Support Document September 2011 

HRS Section 2.3, Likelihood of release, states in relevant part: 

Establish an observed release either by direct observation of the release of a hazardous substance 

into the media being evaluated (for example, surface water) or by chemical analysis of samples 

appropriate to the pathway being evaluated (see sections 3, 4, and 6). The minimum standard to 

establish an observed release by chemical analysis is analytical evidence of a hazardous substance 

in the media significantly above the background level. Further, some portion of the release must 

be attributable to the site. Use the criteria in table 2–3 as the standard for determining analytical 

significance. [emphasis added] 

HRS Section 4.1.2.1.1, Observed release, directs the scorer to establish an observed release to surface water by 

demonstrating that the site has released a hazardous substance to surface water, based on either direct observation 

or chemical analysis. Regarding attribution, this section states in part, 

Some portion of the significant increase must be attributable to the site to establish the observed 

release. . . .” 

Pages 64 through 66 of the HRS documentation record at proposal discussed attribution at this site. It stated in 

relevant part: 

Elevated concentrations of PCBs were detected in samples collected from the AWI drainage ditch 

as well as along the entire length of the drainage easement, which begins just below where the 

drainage ditch ends at PPE 1 (Ref. 7, Appendix A, Figure 3, p. A-3; 7, Appendix B, Table 11, pp. 

B-24 through B-30; 7, Appendix D, p. D-5) (see Figures 2 and 3 of this HRS documentation 

record). None of the sediment samples collected from AIP’s western drainage ditch, upstream of 

its convergence with the AWI drainage easement (DD-502-SD, DD-503-SD, DD-504-SD, and 

DD-505-SD), contained PCBs (Ref. 7, Appendix A, Figure 3, p. A-3; Appendix E, pp. E-1255, E1257, E-1259, E-1261). Therefore, PCBs detected in the observed release are at least partially 

attributable to Source No. 1. 

Source samples collected from Source No. 1 (WWTP landfill) during the EPA 2009 SI were 

analyzed only for PCBs. Sediment sample DD-501-SD, collected from the AWI drainage ditch 

just as it leaves the property boundary of the AWI northern parcel and before it receives runoff 

from other possible sources upgradient of AWI, contained SVOCs and metals in addition to 

PCBs. These constituents were also detected in samples collected from Source No. 2 (the 

commingled AWI remote landfill and the FMNOL) (Refs. 7, Appendix A, Figure 3, p. A-3; 7, 

Appendix B, Tables 11 and 12, pp. B-24 through B-33; 7, Appendix E; 8, Appendix B, Tables 5 

through 8, pp. B-8 through B-32). 

Sediment samples collected from palustrine forested wetlands in the drainage easement contained 

SVOCs, PCBs, and metals, including benzo(a)anthracene (up to 7,100 μg/kg), benzo(a)pyrene 

(up to 6,600 μg/kg), benzo(k)fluoranthene (up to 6,100 μg/kg), indeno(1,2,3-cd)pyrene (up to 

5,700 J μg/kg), phenanthrene (up to 4,600 μg/kg), pyrene (up to 12,000 μg/kg), PCB-1248 (up to 

14,000 J- μg/kg), PCB-1260 (up to 750 μg/kg), cadmium (up to 12 mg/kg), chromium (up to 31 

mg/kg), lead (up to 110 mg/kg), and manganese (up to 960 mg/kg) (Ref. 7, Appendix A, Figure 3, 

p. A-3; 7, Appendix B, Tables 11 and 12, pp. B-24 through B-33). 

The same hazardous substances detected in samples from the AWI remote landfill (southern 

parcel of the AWI property) were also detected in the FMNOL, including benzo(a)anthracene, 

benzo(a)pyrene, benzo(k)fluoranthene, chrysene, fluoranthene, pyrene, PCB-1254, cadmium, 

chromium, lead, and manganese (Refs. 7, Appendix E; 8, Appendix B, Tables 5 through 8, pp. B11 
Armstrong World Industries NPL Listing Support Document September 2011 

8 through B-32) (see Table 4 of this HRS documentation record). The area is prone to frequent 

flooding, potentially resulting in migration of hazardous substances from the commingled landfill 

to the surrounding area, because the commingled landfill is located within the 100-year floodplain 

of Rocky Creek (Refs. 38; 39) and is severely eroded (Refs. 7, Appendix D, p. D-4; 9, p. 6; 19, p. 

20). 

. . . . 

Source No. 3 sample locations FML301, FML305, FML308, FML309, and AWI216 are all 

located within HRS eligible wetlands (palustrine forested) (Refs. 7, Appendix A, Figure 3, p. A3; 52; 60). Samples collected from these locations contained elevated concentrations of 

benzo(a)anthracene, benzo(a)pyrene, benzo(k)fluoranthene, chrysene, fluoranthene, pyrene, PCB1248, PCB-1254, PCB-1260, cadmium, chromium, lead, and manganese (Refs. 7, Appendix E; 8, 

Appendix B, Tables 5 through 8, pp. B-8 through B-32) (see Table 9 of this HRS documentation 

record). 

As cited above, hazardous substances detected in Sources 1, 2 and 3 have also been detected in releases to surface 

water. The significant increase of hazardous substances found in the release can be attributed to the AWI site for 

the following reasons: 

• As discussed in Section 3.1, Site Description, of this support document, evidence of hazardous substance 

deposition into Sources 1 and 2 has been established as the result of processes at the AWI facility. These 

hazardous substances have been detected in release samples. 

• Direct deposition of waste material containing hazardous substances in the observed release samples was 

documented within wetlands, which are part of the surface water migration (see HRS Section 4.0.2 of the 

surface water pathway which identifies that in an HRS evaluation surface water includes wetlands 

adjacent to streams2

). This documents that hazardous substances in the observed release originated from 

the site. 

• Background samples taken within Rocky Creek screen out the potential influence from off-site sources 

upgradient and west of the AWI facility. Detections of hazardous substances within the observed release 

samples were significantly greater than background levels in these upgradient samples (see Section 

4.1.2.1.1 of the HRS documentation record at proposal). 

• Hazardous substances from potential off-site sources associated with the AIP property may be 

contributing to the surface water migration pathway downstream of some release sample locations, 

through Drainage Ditches 3 and 4 (see Figure 3 of Reference 7 of the HRS documentation record). 

However, a significant increase of hazardous substances was established in release samples upgradient of 

the influence of these drainage ditches. That is, release samples DD-507-SD, DD-508-SD, DD-510-SD 

and RC-405-SD were documented to contain hazardous substances significantly greater than background 

levels – outside of the influence of Drainage Ditches 3 and 4 which drain the AIP property. The AIP 

property was identified on page 52 of the HRS documentation record as containing PCBs in three 

“isolated soil sample locations on the northern portion of the AIP property,” yet no PCBs were detected in 

any of the drainage ditches emanating from the AIP property. 

 

2

 HRS Section 4.0.2, Surface water categories, states: 

 ... 

Rivers include: 

• Perennially flowing waters from point of origin to the ocean or to coastal tidal waters, whichever comes 

first, and wetlands contiguous to these flowing waters. 

12 
Armstrong World Industries NPL Listing Support Document September 2011 

13 

• Sediment samples (DD-502-SD, DD-503-SD, DD-504-SD and DD-505-SD) collected from the western 

ditch of the AIP property (see Drainage Ditch 2, as displayed on Figure 3 of Reference 7 of the HRS 

documentation record), did not contain PCBs. PCBs were detected along the entire length of the drainage 

ditch downgradient of Source 1 and its associated PPE, which highlights the conveyance of hazardous 

substances to surface water from Source 1. Although samples DD-502-SD, DD-503-SD, DD-504-SD and 

DD-505-SD were not specifically designated as release background samples, they serve to screen out the 

influence of hazardous substances emanating from the western portion of the AIP property. 

For these reasons, the significant increase of hazardous substances to the surface water migration pathway has 

been attributed to the site because site sources containing hazardous substances resulting from AWI operations 

have been observed within the surface water migration pathway; observed release samples are documented as 

containing hazardous substances downstream of site sources and upstream of off-site sources (such as the AIP 

property); and, the significant increase of hazardous substances in observed release samples cannot be attributed 

to any off-site source. 

This comment has no effect on the HRS site score or the decision to place the site on the NPL. 

4. Conclusion 

The original HRS score of this site was 50.00. Based on the above response to comments, the score remains 

unchanged. The final scores for the Armstrong World Industries site are: 

 Ground Water Not Scored 

 Surface Water 100.00 

 Soil Exposure Not Scored 

 Air Not Scored 

HRS Site Score 50.00